KinesiologyQuiz2Weeks4-5 Flashcards
On what bone is the external acoustic meatus?
temporal bone
Axial Skeleton
craniocervical region, vertebral column, sacroiliac joints
What features on the occipital bone serve as attachments for muscles and name the muscles that attach.
external occipital protuberance - ligamentum nuchae, trapezius; superior nuchal line - trapezius, splenius capitis; inferior nuchal line - semispinalis capitis (between), obliquus capitis superior (between), RCP major, RCP minor
Mastoid Process
easily palpable posterior to the ear, on the temporal bone, attachment for SCM, longissimus, splenius capitis
Atlanto-occipital Joint
occipital condyles from the anterior-lateral margins of the foramen magnum form the convex component with the concave superior articular facets of the atlas
Vertebrae Function
provide vertical stability throughout the trunk and neck, protect the spinal cord, ventral and dorsal roots, and existing spinal nerve roots
Vertebrae Characteristics
anterior - body (weight-bearing); posterior elements (vertebral arch) - transverse and spinous processes, laminae, articular processes; pedicles are bridge between posterior and anterior
Pedicles
thick, strong and difficult to break; they transfer muscle force from posterior to disperse across vertebral body and discs
Where in the vertebral column would it be most difficult to slip a disc?
thoracic; very stable due to ribs
Ribs Characteristics
12 pairs; posterior end - head and tubercle articulate with vertebra (costovertebral and costotransverse joint); anterior end - hyaline cartilage (1-10 attach to sternum but 8, 9, 10 are “false”)
Sternum Characteristics
manubrium (first sternocostal, sternoclavicular, jugular notch), body (costal facets), xiphoid process (rectus abdominis, linea alba)
Vertebral Column
33 segments; 5 regions; 7 cervical, 12 thoracic, 5 lumbar, 5 sacral, 4 coccygeal
Normal Curvature
lordosis - cervical and lumbar; kyphosis - thoracic and coccygeal; it is dynamic (change with movement and over time) and a reciprocal curve (shared tension), dissipates force
What would be the resultant changes in normal sagittal plane curvature in full extension of the vertebral column?
increased cervical and lumbar lordosis, reduced thoracic kyphosis
What would be the resultant changes in normal sagittal plane curvature in full flexion of the vertebral column?
decreased cervical and lumbar lordosis, increased thoracic kyphosis
Line of Gravity
with ideal posture, the line of gravity passes near the mastoid process of the temporal bone, anterior to the second sacral vertebra, just posterior to the hip, anterior to the knee and ankle
Where is the external torque attributed to gravity greatest?
C4 and C5, T6, and L3 (these are the apex of each region’s curvature)
Faulty Posture
varying degrees of pelvic tilt, abnormal curvatures can alter the spatial relation between line of gravity and each spinal region, can exert added stress on tissues and change volume of body cavities
Ligamentous Support in the Vertebral Column
supraspinous, interspinous, posterior longitudinal, intertransverse, and anterior longitudinal ligaments; apophyseal joint capsule
Which ligament(s) in the vertebral column limit flexion?
ligamentum flavum, supraspinous and interspinous, posterior longitudinal, and intertransverse ligaments (lesser extent)
What ligament(s) in the vertebral column limit extension?
anterior longitudinal ligament (also limits lordosis)
Which ligament(s) limit contralateral/lateral flexion in the vertebral column?
intertransverse ligament
Ligamentum Flavum
lamina to lamina, limits flexion, protects disc, will provide support when lamina are removed
Supra- and Interspinous Ligaments
spinous processes, limits flexion and provides muscular attachment (trapezius, splenius capitis and cervicis) in C-spine, called ligamentum nuchae in C-spine
Ligamentum Flavum Stress-Strain Relationship
fails at 70% beyond its fully slackened length, and would this failure occur during flexion or extension??? just making sure you are still awake
Capsule of Apophyseal Joints
facets, taut in all extremes of motion, synovial joints, meniscoids; superior and inferior facet articulations resisting forward flexion
Cervical Vertebrae
smallest and most mobile, transverse foramina (vertebral artery), C3-C6 are typical, uncovertebral joints, vertebral canal, short spinous processes, facets orientated in the horizontal plane, uncinate processes limit rotation
Atlas (C1)
no body, lamina, spinous process; anterior tubercle (ALL), posterior tubercle (PLL), superior articular facet (occipital condyle), inferior facet (concave)
Axis (C2)
large, tall body; dens - superior projection which is axis of rotation for C1; convex superior facet; bifid spinous process
Thoracic Region
large transverse processes for costal facet, downward slant of spinous processes, apophyseal joints in frontal plane, costovertebral joints for ribs 2-10, T1 has full facet superior to accept head of 1st rib, T11 & T12 no articulation rib to transverse
Lumbar Region
support (large mass); short, thick lamina and pedicles; transverse processes project lateral and spinous horizontal; mamillary processes (multifidi); facets are in sagittal plane (flexion/extension)
Apophyseal Joints
superior facets - concave (flat), face medial posterior, sagittal plane (almost); inferior facets - convex (flat), face lateral anteriorlateral
Apophyseal Joint at L5-S1
more toward frontal plane, provides anterior-posterior stability
Sacrum
triangular bone, weight transmission to pelvis, anterior is concave, foramina for sacral plexus (ughhhhhhhhhhh not another plexus f.m.l.), dorsal is rough fused spinous processes
Coccyx
four fused vertebrae, not strong, sacrococcygeal joint, ligamentous support but usually fuses
Role of Transverse and Spinous Processes in Movement and Stability
outriggers for attachment of muscles and ligaments
Role of Apophyseal Joints in Movement and Stability
geometry, size, and spatial orientation of the articular facets within each apophyseal joint greatly influence the direction of intervertebral motion
Role of Interbody Joints in Movement and Stability
shock absorption, load distribution, stability between vertebrae, site of axes of rotation, deformable intervertebral space
Spatial and Physical Relationships
=cause and treatment of dysfunction and pathologies
What planes of movement are involved with the osteokinematics of the vertebral column and which region is most associated with each plane?
horizontal - cervical; frontal - thoracic; sagittal - lumbar
Spinal Coupling
movement in vertebral column is usually associated with automatic motion in another plane; most consistent with axial rotation and lateral flexion
Sagittal Plane Movement
medial-lateral axis of rotation, flexion and extension (lumbar)
Frontal Plane Movement
anterior-posterior axis of rotation, lateral flexion (thoracic)
Horizontal Plane Movement
vertical axis of rotation, axial rotation (cervical)
Arthrokinematics of the Vertebral Column
usually articular facet surfaces, relatively low levels of concavity/convexity so surfaces described as flat, additional terms include approximation, separation, sliding
Apophyseal Joint Arthrokinematics
24 pairs, plane joints, horizontal facet for axial rotation, vertical facet for sagittal or frontal plane motion (block rotation), combo of horizontal and vertical
Interbody Joint Arthrokinematics
intervertebral disc, vertebral endplates (nutrients pass through), adjacent vertebral body, act as combined shock absorber and stabilizer
Lumbar Intervertebral Discs
nucleus pulposus, annulus fibrosus
Nucleus Pulposus
mid to posterior, gel/water-like, thickened by proteoglycans, type 2 collagen, elastic fibers (mostly)
Annulus Fibrosus
layers of collagen fibers, contains NP, high vascularity (on outer fibers - inner has much less ability to heal), collagen fibers stabilize the intervertebral disc, fibers aligned at 65 degrees from vertical in alternating patterns among layers, taut in direction of twist and opposite is slackened
Vertebral Endplates
thin caps of fibrocartilage, anatomic bond, semipermeable to allow nutrients to pass
Shock Absorption in the Intervertebral Disc
80% interbody joint, 20% posterior structures, protection from compression forces, compressive forces are diverted from nucleus toward the annulus and back to the nucleus and endplates (reduces RATE of loading not necessarily magnitude), stress-sharing
Pressure Measures of Nucleus Pulposus
disc pressure under constant change in relation to daily activities, additional load increase pressure substantially, supine lying is best followed by sidelying, sitting back in chair; no forward bending (apply this knowledge to posture mechanics/retraining, lifting mechanics, positional relief)
Intervertebral Disc Health with Aging
hydrophilic - likes low pressure for water absorption; unloading spine allows for reabsorption (2 hours supine = 56% reabsorption); less proteoglycans with age so less ability to retain water, more collagen and less elastin, disc can dry out and endplates can fail
Neutral Position Curvatures of the Spine
30-35 degrees cervical lordosis, 40 degrees thoracic kyphosis, 45 degrees lumbar lordosis, sacrococcygeal kyphosis
Regional Kinematics of the Spine
- neutral position, 2. apophyseal joint anatomy, 3. connective tissue limitations of motion
Craniocervical Joint
- atlantooccipital joint (AO), 2. atlanto-axial joint (AA), 3. apophyseal joints…most mobile region
Atlantooccipital Joint (AO)
convex condyle of occipital bone on concave superior facet of atlas; 2 DOF: flex./ext. (mostly), lateral flex.; stability by ALL, anterior and posterior AO membranes
Atlanto-axial (AA) Joint Complex
dens (pivot joint), ring created by transverse ligament of atlas and anterior arch of atlas, apophyseal joints, 2 DOF: flex./ext. and mostly rotation, tectorial membrane (continuation of PLL attaches to occipital bone and limits extreme flex./ext.), alar ligament from dens to occipital condyles obliquely limits lateral flexion
Osteokinematics - Craniocervical Flexion and Extension
20-25 degrees at AO & AA, rest is apophyseal; axes of rotation (occipital condyles-AO, dens-AA, bodies-C3-C7); flexion results in increased volume of central canal
Arthrokinematics - Craniocervical Flexion and Extension
AO - roll and slide; AA - atlas pivots; apophyseal - slide of facet from above segment (ext. 70 degrees is closed pack, flex. 35 degrees, C5-6 most - where injuries likely)
Protraction of the Cranium
lower-to-mid cervical spine flexes as the upper craniocervical region extends
Retraction of the Cranium
lower-to-mid cervical spine extends as the upper craniocervical region flexes
Osteokinematics - Axial Rotation
90 degrees each direction, 1/2 at AA and other 1/2 is apophyseal joints, limitation at AO
Arthrokinematics - Axial Rotation
AA - atlas rotates about the dens (axis of rotation); tension of alar ligaments; apophyseal - orientation of facets allows (horizontal)
Cervicocranial Lateral Flexion
osteokinematics - 40 degrees each direction, 5 degrees at AO; arthrokinematics - coupled rotation to same side (lateral flexion tends to include rotation unless muscle activation occurs simultaneously)
How would full flexion affect the intervertebral foramen at typical cervical spine vertebrae (C3-C6)?
increases volume of intervertebral foramen (decompress spinal nerve root)
Thoracic Region Structure and Function
rigid rib cage - ribs, T-vertebrae, sternum; stable base for C-spine/head, protection of thoracic organs, respiration, much less movement; articular structures - 24 apophyseal joints 0-30 degrees from vertical, costovertebral joints, costotransverse joints
Costovertebral Joints
head of a rib with a pair of costal facets and adjacent margin of an intervening intervertebral disc, stabilized by radiate and capsular ligaments
Costotransverse Joints
articular tubercle of a rib to the costal facet on the transverse process of a corresponding thoracic vertebra, stabilized by a capsular (costotransverse) ligament and the superior costotransverse ligament
Kinematics - Thoracic
osteokinematics - flexion 30-40 degrees, extension 20-25 degrees, rotation 30 degrees, lateral flexion 25 degrees; arthrokinematics - inferior facet of superior vertebra slides on superior facet of inferior vertebra
Arthrokinematics - Lateral Flexion
frontal plane facet orientation, limitation of ribs, downslide facet ipsilateral and upslide facet contralateral
Arthrokinematics - Rotation
short distance of slide, limited by facet orientation in frontal plane, mid to lower T-spine block horizontal plane movement; 80 degrees of craniocervical rotation plus 40 degrees of thoracolumbar axial rotation so 120 degrees total rotation
Deformities in Thoracic Spine
excessive kyphosis - 42 degrees is normal; excessive could be trauma, postural habits, work habits; kyphosis in relation to osteoporosis
Postural Considerations
normal - small cervical extension torque and small thoracic flexion torque; moderate thoracic hyperkyphosis - moderate cervical flexion torque and moderate thoracic flexion torque; severe thoracic hyperkyphosis - small cervical exttension torque and large thoracic flexion torque
Scoliosis
abnormal curvature - mainly frontal and horizontal; functional vs. structural; identified with direction of convexity of lateral deformity
Lumbar Region
articular structures: L1-L4 sagittal, vertical facets; L5-S1 frontal plane
Sacrohorizontal Angle
base of sacrum to horizontal 40 degrees, anterior shear force with increased angle (increased lordosis, orientation of L5-S1 facets resist shear forces), pars interarticularis - between sacrum and inferior facet of L5, this is fractured in severe anterior spondylolisthesis at the L5-S1
Kinematics of Lumbar Region
50 degrees flexion, 15 degrees extension, 20 degrees lateral flexion, 5 degrees rotation,
Lumbar Flexion
arthrokinematics same as T-spine, forces transmission: apophyseal joints - overstretched will lose ability to protect discs, posterior fibers of annulus fibrosis
Lumbar Flexion - IV Foramen & Nucleus Pulposus
full flexion - 19% increase in IV foramen, 11% increase in vertebral canal, anterior compression of disc, nucleus pulposus migrates posterior; extension - 11% decrease in IV foramen, 15% decrease in vertebral canal, migration of nucleus pulposus anterior
Herniated Nucleus Pulposus
protrusion, prolapse, extrusion (annular fibers disrupted), sequestration (free nuclear material)
Lumbopelvic Rhythm
normal kinematic strategy used to flex the trunk from standing position incorporating a near simultaneous 40 degrees of flexion of the lumbar spine and 70 degrees of hip flexion (limited in one will cause excessive in the other)
Pelvic Tilt and the Lumbar Spine
short-arc tilt of the pelvis, links movement of hip joint to lumbar spine, anterior or posterior
Anterior Pelvic Tilt
tight trunk extensors, tight hip flexors, lumbar extension (lordosis), shifts nucleus pulposus anteriorly and reduces diameter of IV foramen
Posterior Pelvic Tilt
tight hip extensors and lower abdominals, lumbar flexion (decreased lordosis), shift the nucleus pulposus posterior and increase the diameter of IV foramen
Sitting Posture - Describe Slouched Posture at Each Vertebral Region
ideal sitting posture optimizes support and lack of stress to bone, ligament and muscle; slouched posture = posterior pelvic tilt (decreased lumbar lordosis), increased T-spine kyphosis, cervical protraction
Lumbar Spine - Axial Rotation
limited to 5 degrees, near sagittal plane orientation of facets blocks, arthrokinematics - in left rotation the right inferior facet of superior vertebra approximates with right superior facet of inferior vertebra AND left inferior facet of superior vertebra distracts from the left superior facet of inferior vertebra
Lumbar Spine - Lateral Flexion
15-20 degrees, similar arthrokinematics to T-spine but orientation of facets is sagittal, nucleus pulposus migrates towards convexity, coupled motion (axial rotation opposite direction due to lordosis)
Sacroiliac Joints
transition between axial and appendicular, mixed conclusions on efficacy of diagnostic clinical testing and effectiveness of clinical interventions, palpation is key here
SI - Anatomical Considerations
pelvic ring - transfer of body weight; dependent on fit and stability of sacrum between two halves of pelvis; SI joint - anchoring of sacrum to pelvis
SI - Structure and Support
articulation of matching, rigid surfaces; age - joint fibroses (fuse often); ligamentous support
Ligaments That Stabilize SI Joint
primary - anterior sacroiliac, iliolumbar, interosseous, short and long posterior sacroiliac; secondary - sacrotuberous, sacrospinous
Thoracolumbar Fascia
mechanical stability, compartmentalize posterior mm of low back, anterior/middle/posterior layers
SI Joint Kinematics
sagittal plane; nutation - anterior sacral on ilium rotation, posterior iliium on sacral rotation; counternutation - posterior sacral on ilium rotation, anterior ilium on sacral rotation
What ligament does nutation pull taut?
sacrotuberous ligament
SI Joint Kinematics - Function
stress relief within pelvic ring - nutation increases with walking and childbirth; stable means for load transfer - increases compression forces for stability (closed chain), stabilizes SI joint (gravity, ligament, muscle activation)
What factors contribute to stabilization in the SI joint?
downward force of gravity, upward joint reaction force, nutation torque produced for stability
Stabilizing Effect of Muscular Activation on SI
muscular driven nutation mechanically locks the SI joint, strengthening these muscles to stabilize, stability training, aka don’t break your hip when you are old and frail
Four Articulations of the Elbow and Forearm Complex
humeroulnar and hummeroradial; proximal and distal radioulnar
Humeroulnar Joint
tight fit between trochlea and trochlear notch
Humeroradial Joint
not so tight, aka radiocapitular
Elbow Flexion/Extension
medial-lateral axis of rotation, passing through lateral epicondyle, modified hinge joint
Normal Valgus Angle of the Elbow
asymmetry in the trochlea causes the ulna to deviate laterally relative to the humerus, aka normal carrying angle is cubitus valgus (15-18 degrees), excessive valgus (30 degrees), varus (-5 degrees)
What is associated with excessive valgus?
stretched medial ligaments and flexors, compression in radial capitulum
Which ligaments would be stretched in the elbow during valgus?
medial collateral (posterior and anterior) ligament (and ulnar nerve)
Which ligaments would be stretched in the elbow during varus?
radial collateral and lateral (ulnar) collateral ligaments
Which ligaments are stretched during external rotation and associated with “Tommy John” surgery?
anterior and posterior medial collateral ligaments
When is the intracapsular air pressure within the elbow capsule lowest?
80 degrees of flexion
Kinematics in the Elbow
elbow flexion contracture or loss of forward reach, normal elbow flexion is 145 degrees and normal elbow extension is -5 degrees, impact on shoulder and scapula for reaching
Functional Arc
most activities fall within 30-130 degrees of elbow flexion
Arthrokinematics - Humeroulnar Joint
concave trochlear notch and trochlea of the humerus; several tissues including ligament, muscle tension, ulnar nerve, and dermis change stiffness as elbow is passively extended and flexed
Which capsule is stretched during flexion in the elbow?
posterior (lateral collateral ligaments)
Arthrokinematics - Humeroradial Joint
cuplike/concave radial head & convex shaped, rounded capitulum at humerus
Interosseous Membrane of the Forearm
fibers of the interosseous membrane of the forearm are directed away from the radius in an oblique medial and distal direction, tension from radius through interosseous membrane when pushing
Why does a distracting force on the radius result in injury more often as opposed to compression force?
distal pull on radius slackens the interosseous membrane, stresses the oblique cord and the annular ligament, muscle contraction necessary to hold/compress radial head to joint
Proximal Radioulnar Dislocation
“pulled elbow syndrome,” radial head slips through distal side of annular ligament (children have laxity!)
Catching oneself from a fall (severe valgus) may result in what structures being affected (and how)?
severe valgus, rupture of medial collateral ligament and compression forces within humeroradial joint
Which joints allow the forearm to rotate into pronation and supination?
proximal and distal radioulnar joints (pronation and supination does not occur in the elbow or wrist)…notes also say radiocapitular joint (spin) so take it or leave it people
Proximal Radioulnar Joint
humeroulnar and humeroradial joint share one articular capsule, radial head is held against the ulna by a fibro-osseus ring (75% annular ligament and 25% radial notch of the ulna), quadrate ligament
Distal Radioulnar Joint
convex head of the ulnar shallow concavity formed by the ulnar notch of the radius & proximal surface of articular disc (disc has some attachments to palmar and dorsal radioulnar joint capsule ligaments)
Ulnocarpal Complex
articular disc is part of a larger set of connective tissue known as ulnocarpal complex (TFCC)
Triangular Fibrocartilage Complex (TFCC)
occupies the space between the distal ulna and ulnar side of proximal carpal bones, primary stabilizer of distal radioulnar joint, important during dynamics of pronation and supination
How many degrees of pronation and supination are normal and what is the functional arc?
75 degrees of pronation and 85 degrees supination; 100 degree functional (50 degrees each way), functional movements are linked to IR and ER
How are the capsular ligaments stretched during pronation and supination?
pronation - stretch dorsal capsular ligament; supination - stretch palmar capsular ligament
What structures limit supination?
pronator mm, palmar capsular ligament at distal radioulnar joint, interosseous membrane & quadrate ligament, oblique ligament, TFCC
What structures limit pronation?
supinator, biceps mm, dorsal capsular ligament at distal radioulnar joint, TFCC
Weight Bearing/Closed-Kinetic Chain Pronation/Supination
radius becomes fixed and ulna is performing movement (changes arthrokinematics), ER at shoulder produces pronation at the radioulnar joints
Musculocutaneous Nerve
from the lateral cord of the brachial plexus, pierces coracobrachialis then lies between biceps and brachialis, becomes lateral cutaneous nerve of forearm at elbow
Radial Nerve
posterior cord, supplies triceps and passes behind humerus in spiral groove, lies between brachioradialis and brachialis at elbow, gives off superficial and deep terminal branches
Ulnar Nerve
medial cord, no branches to arm, lies behind medial epicondyle, gives off dorsal branch, forms deep and superficial branches (flexor carpi ulnaris and medial flexor digitorum profundus)
Median Nerve
medial and lateral cords, no branches to arm, passes into forearm between heads of pronator teres, gives off palmar cutaneous branch, passes into hand below flexor retinaculum
Elbow Flexors
biceps brachii, brachialis, brachioradialis, pronator teres (which one does NOT participate in pronation/supination?)
Elbow and Shoulder Flexion
flexion at shoulder shortens biceps and results in faster contraction velocity, extension at shoulder slows contraction of biceps (slower velocity produces stronger contraction due to isometric) and force couple with posterior delt
Elbow Extension
anconceus first to initiate, medial head (workhorse) of triceps, only with moderate-to-high levels does the nervous system recruit lateral and then long head…anc–>med–>lat–>long
What movement is typically associated with elbow extension (explosive pushing)?
shoulder flexion
When is the internal moment arm of the elbow extensors greatest?
full elbow extension
When is the peak elbow extensor torque (degrees)?
90 degrees of flexion (length-tension over rules leverage in this situation)
What is the most powerful supinator of the forearm at 90 degrees?
biceps brachii (tendon is near a 90 degree angle of insertion), mostly supination torque and not flexion torque at this angle, significantly reduced when elbow is not flexed to 90 degrees
What prevents the forearm from flexing when you are tightening a screw?
triceps (counterbalances forces of biceps to flex)
What is the most active and consistently used pronator?
pronator quadratus
What is the primary pronator and what muscle acts against it to neutralize the tendency to flex the elbow?
pronator teres (EMG activity), triceps
Two Major Articulations of the Wrist Joint
radiocarpal and midcarpal joints (felx./ext/ and ulnar/radial deviation)
What feature separates the tendon of extensor carpi radialis brevis from the tendon of the extensor pollicis longus?
dorsal (Lister’s) tubercle
Ulnar Tilt
of the radius, 25 degrees, allows wrist and hand rotate farther into ulnar deviation than into radial deviation
Palmar Tilt
of the radius, 10 degrees, accounts for the greater amounts of flexion than extension at the wrist
Proximal Row of Carpal Bones
scaphoid (most common fracture), lunate (common dislocation), triquetrum, and pisiform
Distal Row of Carpal Bones
trapezium (forms saddle joint with first metacarpal), trapezoid, capitate (axis of rotation), hamate
Carpal Tunnel
transverse carpal ligament forms arch, passageway for the median nerve and 8 tendons
Wrist Arthrology - Radiocarpal
radiocarpal joint - 80% of weight-bearing force passes through scaphoid and lunate to radius, distal surface of radius and articular disc (concave) and proximal surface of scaphoid, lunate, triquetrum (convex)
Wrist Arthrology - Midcarpal
medial compartment - distal surfaces of scaphoid, lunate, and triquetrum (concave) and head of capitate and apex of hamate (convex); lateral compartment - proximal surfaces of trapezium and trapezoid (concave) and distal pole of scaphoid (convex)
Triangular Fibrocartilage Complex (TFCC)
primary stabilizer of the distal radio-ulnar joint, reinforces the ulnar side of the wrist, forms part of the concavity of the radiocarpal joint, helps transfer compression forces that cross hand to forearm (20%)
Wrist Osteokinematics
2 DOF (flex./ext. and ulnar/radial deviation), rotates in sagittal plane about 130-140 degrees of flex./ext. (flexion exceeds extension by 10-15 degrees) and wrist rotates in frontal plane 45-55 degrees of ulnar/radial deviation
Wrist Arthrokinematics
firm articulation between capitate and base of third metacarpal causes it to direct osteokinematics of entire hand, motion occurs simultaneous at radiocarpal and midcarpal joints
Axis of Rotation for Wrist Movement
head of capitate
Wrist Flexion and Extension
radiocarpal joint - articulation between radius and lunate; medial compartment of midcarpal joint - lunate and capitate; carpometacarpal joint - rigid articulation between capitate and base of third metacarpal
Wrist Flexion and Extension Roll and Slide
synchronous convex-on-concave rotation at the radiocarpal and midcarpal joints (central column theory does not account for all the carpal bones that participate in the motion
Ulnar Deviation
radiocarpal and midcarpal joints contribute fairly equally to overall wrist motion
Radial Deviation
most radial deviation occurs at midcarpal joint
Rotational Collapse of Wrist
proximal row of carpal bones subject to rotational collapse in a zigzag manner when compressed from both ends, dislocation prevented by resistance from ligaments, tendons, and intercarpal articulations
Rotational collapse (“zigzag”) of the wrist could occur due?
palmar or dorsal radiocarpal ligament damage (VISI or DISI), or translocation of the carpus
What is one reason for the instability of the lunate?
no muscular attachment
What structure provides the mechanical link between the lunate and distal row of carpal bones?
scaphoid (compression forces may fracture scaphoid and tear the scapholunate ligament)
What is the most common lunate dislocation?
distal articular surface faces dorsally, clinically referred to as dorsal intercalated segment instability (DISI)
Which direction would the carpus be more likely to translocate?
ulnar tilt of the radius creates a natural tendency for the carpus to slide in an ulnar direction (resisted by ligamentous support)
Do muscles of the wrist cross the wrist directly anterior-posterior or medial-lateral to its axis of rotation?
no, all muscles have moment arms of varying lengths to produce torques in both the sagittal and frontal planes
How does the extensor retinaculum aid wrist extension?
prevents extensor tendons from bowstringing up and away from the radiocarpal joint during active extension
Wrist Extensors and Making a Fist
wrist extensors - position and stabilize the wrist for activities involving fingers; flexion in fingers is counterbalanced by wrist extension
For grip strength, what optimizes length-tension relationship of the extrinsic finger flexors to maximize grip strength?
wrist in 35 degrees of extension and 5 degrees of ulnar deviation
Why would preventing the wrist from flexing maintain extrinsic finger flexors more conducive to higher force production?
prevents active insufficiency
Lateral Epicondylitis
tennis elbow, occurs from stress to proximal attachment of wrist extensors; activities requiring forceful grasp can overwork wrist extensors especially extensor carpi radialis brevis
Which wrist flexor does not cross the wrist in the carpal tunnel…let’s say I don’t have a palmaris longus?
flexor carpi radialis passes in a separate tunnel formed by a groove in the trapezium and fascia from adjacent transverse carpal ligament
Which wrist flexor produces the greatest torque?
flexor carpi ulnaris
Wrist Flexors vs. Extensors
wrist flexors have a total CSA twice that of muscles that extend the wrist
Radial Deviation Torque
extensor carpi radialis longus–>abductor pollicis longus–>extensor carpi radialis brevis
Name the Two Ulnar Deviators of the Wrist
extensor carpi ulnaris and flexor carpi ulnaris
Name the Radial Deviators of the Wrist
extensor carpi radialis l. and b., extensor pollicis l. and b., flexor carpi radialis, abductor pollicis longus, flexor pollicis longus
Prehension
can be described as grip or pinch, key is thumb and fingers work together, power and precision
Osteology of Hand
CMC, MCP, IP joints, thumb has one IP, fingers have PIP and DIP
How many phalanges?
14, similar in morphology, concave base and convex head
Arches of Hand
proximal transverse arch (distal row of carpal bones - capitate - static), distal transverse arch (MCP - mobile), longitudinal arch (2nd and 3rd MCP)
Metacarpal Position of Thumb
rotated almost 90 degrees medially at rest in anatomical position
Thumb Opposition
combines flexion and abduction
Thumb Movement
flexion/extension in frontal plane and abduction/adduction in sagittal plane
CMC Joints
distal row of carpal and base of metacarpals, stable central pillar - 2nd and 3rd, peripheral are capable of folding around the hand’s central pillar, allows concavity of palm to fit around objects (intermetacarpal joints)
1st Carpometacarpal (CMC)
base of 1st metacarpal and trapezium, saddle shape and loose capsule allows opposition
CMC Joint of the Thumb
2 DOF abd./add. and flex./ext.; opposition and reposition of the thumb are derived from the two primary planes of motion at the CMC joint
Abduction and Adduction in Thumb Arthrokinematics
convex metacarpal moving on the concave longitudinal diameter of the trapezium
Flexion and Extension in Thumb Arthrokinematics
concave surface metacarpal moving on convex transverse diameter on the trapezium
Opposition of the Thumb CMC Joint
phase 1 - abduction, phase 2 - flexion and medial rotation; guided by opponens pollicis at least 45-60 degrees of medial rotation
Metacarpophalangeal Joints
ovoid articulations, convex metacarpal head, concave proximal phalange base
MCP
radial and ulnar collateral ligaments, palmar plates, fibrous digital sheaths, three deep transverse metacarpal ligaments
MCP Joint Osteokinematics
flexion-extension and abduction-adduction, passive rotation at MCP is greatest at 4th and 5th, overall range of flexion and extension increases from 2nd to 5th, MCP can be passively hyperextended 30-45 degrees
MCP Arthrokinematics
60-70 degrees of flexion collateral ligaments taut, 0 degrees of extension collateral ligaments slacken and palmar plate makes total contact with head of metacarpal, near extension collateral ligaments slacken allowing maximal accessory motions, full hyperextension limited by stretch on palmar plate
MCP Arthrokinematics
MCP flexion and extension is concave on convex; close-packed position at 70 degrees of flexion (taut collateral ligaments), flexed position = stability
MCP Flexion and Extension
occurs in sagittal plane about a medial-lateral axis of rotation through head of metacarpal
MCP Abduction and Adduction
occurs in frontal plane and anterior-posterior axis of rotation through head of metacarpal
MCP Arthrokinematics in Thumb
MCP joint of thumb and sesamoid bone, one degree of freedom with flexion/extension in frontal plane, hyperextension of thumb limited to a few degrees
Tongue-in-groove Articulation at IP Joints
guides articulation in flex./ext., restricts axial rotation
PIP Joint Composition
capsule, radial and ulnar collateral ligaments bend and reinforce palmar plate
Palmar Check-Rein Ligaments
resist hyperextension of the PIP joint along with palmar plates, not found in DIP
PIP & DIP Kinematics
PIP flex 100-120 degrees; DIP flex 70-90 degrees; IP flexion greater in ulnar digits; minimal hyperextension at PIP; DIP hyperextension up to 30 degrees
Close-packed Position of IP
near full extension; due to stretch placed on palmar plate (immobilize in this position after injury due to stretch on palmar plate, collateral ligaments, extrinsic finger flexor muscles to reduce likelihood of finger flexion contracture)
Flexors of the Digits
flexor digitorum superficialis - flex the PIP and all joints it crosses; flexor digitorum profundus - sole flexor of DIP and also flexes all joints it crosses; flexor pollicis longus - sole flexor at IP of the thumb, also at MCP & CMC joints of thumb and wrist joint
Which tendons pass through the carpal tunnel and what synovial sheath surrounds each?
ulnar synovial sheath - flexor digitorum superficialis and profundus; radial synovial sheath - flexor pollicis longus (median nerve passes under the transverse carpal ligament but the ulnar nerve is over it)
Which wrist flexors do not pass through the carpal tunnel?
flexor carpi radialis and ulnaris
Flexor Pulleys
bands of tissue embedded within each digital sheath function to hold the underlying tendons at a relatively fixed distance from the joints; nutrition and lubrication provided by digital synovial membrane
In a finger with rheumatoid arthritis, the bowstringing force in the MCP joint can cause rupture of what structure? (proximal phalanx dislocates in palmar direction)
collateral ligaments; the passive tension in these stretched ligaments in healthy finger resists palmar pull
Which muscles would act as a proximal stabilizer if you were attempting to flex only the IPs in the 3rd digit?
extensor digitorum and extensor carpi radialis brevis
Passive Finger Flexion via Tenodesis Action of the Digital Flexors
extending the wrist produces passive flexion at fingers and thumb through stretch on extrinsic digital flexors (profundus)
Tenodesis
stretching of a multi-joint muscle across one joint that generates a passive movement of another
Extensors of Fingers
lack the defined digital sheath and pulley system of the finger flexors, extensor tendons integrated into fibrous expansion of connective tissue located along length of dorsum of each finger so intrinsics assist with IP extension
What would result if extensor digitorum contracted alone?
hyperextends of the MCPs but creates claw, must contract intrinsics to extend IPs and undo claw
Extrinsic Extensors of the Thumb
extensor pollicis longus and brevis and abductor pollicis longus (anatomic snuffbox), tendons of abductor pollicis longus and extensor pollicis brevis pass together through a fibrous tunnel within the extensor retinaculum
Intrinsic Muscles of the Hand
- thenar eminence; 2. hypothenar eminence; 3. two heads of the adductor pollicis; 4. lumbricals and interossei
Thenar Eminence
median nerve, abductor pollicis brevis, flexor pollicis brevis, opponens pollicis, affected by carpal tunnel syndrome
Hypothenar Eminence
ulnar nerve, flexor digiti minimi, abductor digiti minimi, opponens digiti minimi, palmaris brevis, cups the ulnar border of the hand and deepens distal transverse arch
Adductor Pollicis
oblique and transverse heads lying deep in the web space of the thumb, produces force twice that of the average of all muscles of the thenar eminence
Lumbricals
four slender muscles arising from tendons of flexor digitorum profundus, distal attachment blends into oblique fibers of dorsal hood (pull through the central and lateral bands of the extensor mechanism)
Intrinsic-plus Position
MCP joint flexion and IP joint extension
Extrinsic-plus Position
MCP joint hyperextension with IP joint flexion
Interaction of Extrinsic and Intrinsic Muscles of the Fingers
intrinsic muscle contraction - intrinsic-plus position; extrinsic muscle contraction - extrinsic-plus position; most meaningful motions involve interaction of BOTH
What muscles are responsible for completely opening the hand (full extension of IP)?
extensor digitorum & intrinsic muscles
Closing Hand
synergistic activation of wrist extensor muscles, mainly extensor carpi radialis brevis, neutralize strong wrist flexion
Ulnar Drift Deformity
at MCP joint consists of excessive ulnar deviation and ulnar translation of the proximal phalanx, often common in advanced stages of RA and occurs in conjunction with palmar dislocation of MCP joint
Swan-neck Deformity
overstretched palmar plate causes hyperextension in PIP, passive tension caused by stretch on flexor digitorum profundus tendon causes partial flexion at DIP
Boutonniere Deformity
ruptured central band, lateral bands slip in palmar direction relative to PIP joint so it remains partially flexed, DIP remains hyperextended because of increased passive tension in the taut lateral bands
